The line comes from 'Cazas Bahiano,' an animation by Mundo Canibal, the Brazilian web animation project of the Piologo brothers. Mundo Canibal became known in Brazil for loud, over-the-top cartoon shorts, and its most shouted catchphrases were ripped into soundboard clips that fans replay on their own. That is how a three-second yell like 'testistarou tostaustaroste' escaped its original cartoon and turned into a standalone meme sound, passed around in edits, streams and group chats.